Dry cell



March 1928.

W. F. HENDRY DRY CELL Filed Jan. 23. 1924 ATTORNEY Patented Mar. 6, 1928.

UNITED STATES PATENT OFFICE.

WILLIAM F. HENDRY, OF OSSINING, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO NATIONAL CARBON COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

DRY

CELL.

Application filed. January23, 1924. Serial No. 688,057.

This invention relates to dry cells and more particularly to a novel method of providing bibulous linings or separators for dry cells.

Two general types of dry cells are ingeneral con'uncrcial use; the so-called paper lined and the bag type cells. In the former the bibulous lining is usually provided in the form of a sheet of paper coated with paste which is placed against the inside of a zinc container electrode. This lining serves physically to separate the depolarizing mixture from the anode without interference with the electrolytic action. Usually, the depolarizing mixture is tamped in the lined zinc can and then the paper is turned down and the cell is sealed. In the bag type cell a bobbin, i. e., the depolarizing mixture molded around a central carbon electrode, is

enveloped in a wrapping of cellulose material (cotton, paper or the like). This bobbin, with its bibulous wrapper, is placed within a slightly larger zinc container electrode. lVhile the bobbin is centrally held within the electrode, paste is poured into the container, filling up the space between the bobbin and the zinc anode.

The objections to both methods are manifold. In the paper lined cell the coating of the paper sheets and the inserting of the paper in the cans are relatively expensive operations. Furthermore, the paper is liable to be injured While the depolarizing mixture is bein tamped or is otherwise being inserted into the container. It has been suggested to apply the paste direct to the zinc can; however, this does not materially'decrease the speed at which the cells may be assembled. In the assembly of the bag type cells complicated and expensive machinery is required to center the bobbin While the paste is being poured into the container and around the bobbin, because otherwise the separating lining would not be uniform throughout the circumference of the cell. Furthermore, the provision of the bibulous i'naterial around the bobbin also entailed considerable expense.

it is theobject of the present invention to obviate some of the drawbacks incident to the assembly of bag type and paper lined dry cells by applying the. bibulous material, preferably in a eomminuted form, direct to mass of depolarizing material and cause it to form an adherent coating thereon. In

accordance with a further feature of the invention t-he bibulous material is applied together with the paste, which may consist of flour, starch or the like.

In accordance with the preferred embodiment of the invention the depolarizing mass is in the form of a bobbin, preferably composed of a plurality of compacted tablets such as are described in my copending application Serial No. 651,611, filed July 30,

The coating to be applied to this bobbin is a mixture of granulated wood pulp, plaster of Paris, diatomaceous earth or the like, acting as a bibulous material; flour, starch, or the like, to form the body of the paste; part of the electrolyte, e. g. zinc chloride; and the necessary quantity of water to render the mixture fairly liquid. The bobbin is coated with this mixture either by dipping it into the mixture, or preferably, by spraying the mixture on the bobbin. The spraying operation will insure the uniform distribution of the mixture around the bobbin and the intimate adherence thereof to the depolarizing mixture. The coating on the bobbin is dried, e. g., by hot air, whereupon it may be placed within the zinc container electrode, the coating being of a uniform width toinsure proper centering of the bobbin with respect to the zinc cup. The assembly of the dry cell may now be completed by adding water or possibly a small quantity of paste and then sealing the cell.

The important steps of the process are illustrated in the drawing in which 2 is a shaft carrying tablets 1 compacted of de polarizing material and separated from each other by means of spacers 3. The tablets are caused to rotate and move in the direction of their axes in front of a sprayer 4 through which a mixture 5 of the above described composition, and contained in a vesscl 6, will be applied around the tablets. The tablets rotate and pass in front of a hot air blast 7. so as to accelerate the drying of the coat. Instead of the arrangement herein disclosed the tablets may be coated also to form a homogeneous mass like a bobbin, in which case the spacers need not be provided, asufficient number of tablets being coated together to permit their insertion into a zinc cup.

Obviously, the same method or methods may be used to coat bobbins of the conventional type, whereby the necessity of rovidglng muslin bags or the like will be 0 viate \Vhen the washers 1 are to be used to make up multiple zinc electrode batteries such as are described in my copending application Serial No. 654,613, filed July 30, 1923, and Serial No. 688,058, filed Jan. 23, 1924, then the separators 3 are omitted and the washers are spaced on shaft 2 so as to insure the covering of the entire surface of washers l with the mixture 5.

\Vhat I claim is:

1. The method of making dry cells which consists in compacting the depolarizing mixture into tablets, applying to said tablets a coating composed of granulated wood pulp,

wood pulp, flour, zinc ehlorid and water and then in front of a blast of heated air, placingthe coated tablets in a zinc electrode. and passing a carbon electrode through said tablets.

In testimony whereof, I have signed my name to this specification, this 22nd day of J anuary, 1924.

\VILLIAM F. HENDRY. 

